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.TH NANOSLEEP 3C "Mar 27, 2016"
.SH NAME
nanosleep, thrd_sleep \- high resolution sleep
.SH SYNOPSIS
.nf
#include <time.h>

\fBint\fR \fBnanosleep\fR(\fBconst struct timespec *\fR\fIrqtp\fR,
     \fBstruct timespec *\fR\fIrmtp\fR);
.fi

.nf
#include <threads.h>

\fBint\fR \fBthrd_sleep\fR(\fBconst struct timespec *\fR\fIrqtp\fR,
     \fBstruct timespec *\fR\fIrmtp\fR);

.SH DESCRIPTION
The \fBnanosleep()\fR and \fBthrd_sleep()\fR functions cause the current thread
to be suspended from execution until either the time interval specified by the
\fIrqtp\fR argument has elapsed or a signal is delivered to the calling thread
and its action is to invoke a signal-catching function or to terminate the
process. The suspension time may be longer than requested because the argument
value is rounded up to an integer multiple of the sleep resolution or because of
the scheduling of other activity by the system. But, except for the case of
being interrupted by a signal, the suspension time will not be less than the
time specified by \fIrqtp\fR, as measured by the system clock,
\fBCLOCK_REALTIME\fR.
.sp
.LP
The use of the \fBnanosleep()\fR and \fBthrd_sleep()\fR functions has no effect
on the action or blockage of any signal.
.SH RETURN VALUES
If the \fBnanosleep()\fR or \fBthrd_sleep()\fR function returns because the
requested time has elapsed, its return value is \fB0\fR.
.sp
.LP
If the \fBnanosleep()\fR function returns because it has been interrupted by a
signal, the function returns a value of \(mi1 and sets \fBerrno\fR to indicate
the interruption. If the \fIrmtp\fR argument is non-\fINULL\fR, the
\fBtimespec\fR structure referenced by it is updated to contain the amount of
time remaining in the interval (the requested time minus the time actually
slept). If the \fIrmtp\fR argument is \fINULL\fR, the remaining time is not
returned.
.sp
.LP
If \fBnanosleep()\fR fails, it returns \fB\(mi1\fR and sets \fBerrno\fR to
indicate the error.
.sp
.LP
The
.B thrd_sleep()
function may fail for identical reasons as the
.B nanosleep()
function and returns \(mi1; however, the C11 standard does not define that
.B errno
should be set, therefore callers of \fBthrd_sleep()\fR cannot rely on
.B errno
being set or staying the same across a call to
.B thrd_sleep() .

.SH ERRORS
The \fBnanosleep()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEINTR\fR\fR
.ad
.RS 10n
The \fBnanosleep()\fR function was interrupted by a signal.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The \fIrqtp\fR argument specified a nanosecond value less than zero or greater
than or equal to 1000 million.
.RE

.sp
.ne 2
.na
\fB\fBENOSYS\fR\fR
.ad
.RS 10n
The \fBnanosleep()\fR function is not supported by this implementation.
.RE

.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	MT-Safe
_
Standard	See \fBstandards\fR(7).
.TE

.SH SEE ALSO
.BR sleep (3C),
.BR time.h (3HEAD),
.BR attributes (7),
.BR standards (7)
